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NCV TVET: Computer-Integrated Manufacturing (CIM) - Key Vocabulary

Question 1

  • Timing and scope
    • Time: 3 HOURS
    • Total marks: 100
    • This is a National Certificate (Vocational) exam paper for Computer-Integrated Manufacturing (CIM) at NQF Level 4, code 6030324, NOV 0324, with 5 pages and 2 information sheets.
  • 1.1 Explain the THREE main subsystems that make up the CNC machine tool.
    • The machine tool subsystem: the physical structure that provides the rigid frame for motion (machine bed, column, saddle, ways, spindle), including the mechanical drive system (axes, ball screws, linear guides) and spindle drive.
    • The control subsystem: the CNC controller that interprets NC programs, controls interpolation, coordinates, and path execution; includes the CNC unit, computer interface, memory, and I/O for signals.
    • The drive/feedback and periphery subsystem: the servo/stepper drives, encoders (feedback sensors) to close the loop, power electronics, cooling, lubrication, and other peripherals (tool changer, clamping, part handling) that enable motion and process execution.
  • 1.2 Draw a CIM system block diagram representing 2 × CNC machine tools, 2 × automated conveyor belts and 3 × industrial robot systems.
    • Central CIM control system (coordinate/monitoring layer) interacts with:
    • CNC Machine Tool 1
    • CNC Machine Tool 2
    • Conveyor Belt 1
    • Conveyor Belt 2
    • Industrial Robot System A
    • Industrial Robot System B
    • Industrial Robot System C
    • Optional integrations (not explicitly shown in the exam text) may include: PLCs, sensors, and a central MES/ERP layer for scheduling and data logging. In the block diagram you should show data flow between the central controller and each tool/robot/conveyor, plus feedback signals from sensors back to the controller.
  • 1.3 Draw a system block diagram of a CNC machine tool with closed-loop control showing the energy and material flow.
    • Energy flow (power): Power Supply → Drive Electronics/Servo Drives → Servo Motors/Ball Screws → Spindle Motor → Cooling/Lubrication pumps as needed.
    • Control loop: Controller receives position/velocity feedback from encoders encased in the servo system and issues drive commands to reach the target coordinates; the feedback path closes the loop for accurate motion.
    • Material flow: Raw stock enters the work zone; cutting process removes material to form chips; finished part moves to a fixture/part-handling system; chips are removed by a chip conveyor or collection system.
    • Interfacing utilities: coolant delivery, lubrication, part clamping/fixturing, and tool changing as part of the peripheral system.

Question 2

  • 2.1 Explain what is meant by the following terms.
    • 2.1.1 Absolute system
    • An absolute coordinate system uses fixed origin coordinates, typically referenced to a workpiece zero or machine zero. Each position is defined relative to that fixed origin, so commands specify absolute positions in the chosen coordinate frame.
    • 2.1.2 Cartesian Coordinates
    • A three-dimensional coordinate system defined by three perpendicular axes: X (horizontal), Y (vertical), and Z (depth). Points in space are given by (X, Y, Z).
    • 2.1.3 Feed Rate
    • The programmed speed at which the cutting tool travels along the programmed path, typically expressed in units per minute, e.g. ext{feed rate} = f ext{ (mm/min or in/min)}. It controls how quickly the tool moves through material.
  • 2.2 Write down the systematic approach to creating a NC part programme.
    • Define part geometry and tolerances from the design/drawing.
    • Establish work coordinate system (workpiece zero) and reference points.
    • Select machine, tooling, fixtures, and cutting parameters (speeds, feeds, depths).
    • Generate tool paths using CAM/CAD data (toolpath strategy, roughing/finishing passes).
    • Write NC program (G/M code) or generate post-processed code from CAM.
    • Simulate/verify the program to check collisions, clearance, and reachability.
    • Transfer program to CNC machine, set up tooling and part in the machine, perform dry-run if possible.
    • Execute and monitor the first run; record offsets, tolerances, and adjustments as required.
  • 2.3 Explain the THREE directions (X, Y, Z) of tool path travel for the three-axis CNC machine tool.
    • X-direction: left-right movement in the horizontal plane.
    • Y-direction: front-back movement in the horizontal plane (perpendicular to X).
    • Z-direction: up-down movement (depth) vertical to the workpiece surface.
  • Study FIGURE 1 and answer the following related questions
    • 2.4.1 Determine the coordinates from the workpiece zero (A to E)
    • The exact coordinates depend on the diagram in FIGURE 1. From the provided transcript, the precise coordinate values are not legible. In practice:
      • Read off the X, Y, Z offsets for each point A–E from the workpiece zero reference.
      • Record coordinates in the chosen work coordinate system for each point.
    • 2.4.2 Redraw the workpiece in FIGURE 1 and include the tool path showing the coordinates worked out in QUESTION 2.4.1.
    • Conceptually: reproduce the same geometry with annotated tool-path coordinates, showing the sequence of moves that the tool will take to follow the path from the workpiece zero to each point A–E, including entry/exit moves and any approach/clearance moves.
    • 2.4.3 Write down the basic structure of the CNC mill program.
    • Begin with program header and setup:
      • Program name and header (e.g., N codes, program name).
      • Select units and plane (e.g., G20/G21, G17).
      • Tool selection and spindle setup (e.g., T01 M06, S speed, M03).
    • Main body of the path:
      • G00 (rapid move) to approach positions.
      • G01 (linear feed) for controlled cuts along straight segments.
      • G02/G03 (circular interpolation) for arcs when needed.
      • Change of tools, cooling, and other M-codes as required.
    • End of program:
      • Return to home or machine reference (e.g., G28), stop spindle (M05), end program (M30).

Question 3

  • 3.1 Industrial Robot basics
    • 3.1.1 What does the acronym TCP represent?
    • Tool Center Point.
    • 3.1.2 What is fitted to the TCP?
    • The end effector (e.g., gripper, suction cup, welding tip, etc.) is fitted to the TCP; it defines the point of reference for a tool’s location in space.
    • 3.1.3 What type of gripper is commonly used to move single flat metal sheets between pressing workstations?
    • A suction/gripper using a vacuum cup (vacuum gripper) is commonly used for handling flat metal sheets.
    • 3.1.4 Indicate the THREE types of motion commands found on industrial robot software
    • PTP (point-to-point)
    • LIN (linear interpolation / straight-line motion)
    • CIRC (circular interpolation / arc motion)
    • 3.1.5 Explain what is meant by the term CONT concerning programming points in industrial robot coding?
    • CONT is used to denote Undefined motion (air movement) in the robot programming language, i.e., motion where there is no defined position change; it marks a non-motion or an initialization/transition state in the code. This corresponds to the diagram description: CONT = Undefined motion (air movement).
    • 3.1.6 Explain what motion command you would use to move the end effector into a confined space?
    • Use a LIN (linear) motion command to move in a straight-line path into the confined space, typically preceded by a safe approach move (e.g., PTP to a pre-qualification position, then LIN into the space) to ensure controlled and collision-free entry.
  • 3.2 Study FIGURE 2 below using simple English statements explaining the sequence of operation.
    • The diagram shows two conveyors, Conveyor 1 and Conveyor 2, with an obstacle between them.
    • Likely sequence (described in simple terms):
    • A workpiece starts on Conveyor 1 and is moved toward the obstacle.
    • The robot picks the workpiece from Conveyor 1 before the obstacle.
    • The robot redirects or moves the workpiece to bypass or clear the obstacle, possibly placing it on Conveyor 2 or re-positioning to allow passage.
    • The sequence completes with the workpiece being transferred to Conveyor 2 after clearing the obstacle.
  • 3.3 Study FIGURE 2 and draw the tool path showing the motion commands you would use to move the workpiece over an obstacle.
    • The path would typically include:
    • A pre-positioning move (PTP) to a safe approach point before approaching the obstacle.
    • A straight-line (LIN) path to cross over the obstacle height, maintaining a clearance above the obstacle if required.
    • A subsequent LIN or PTP move to re-align with Conveyor 2 or the intended destination.
    • Final positioning to place the workpiece on Conveyor 2 and retreat to a safe state.
  • 3.4 Draw the block diagram of the make of an industrial robot system showing data flow.
    • Data flow diagram (textual representation):
    • Sensors/PLC inputs → Robot Controller → Joint Controllers/Servo Drives → Robotic Joints → End Effector (gripper, suction, etc.) → Process (workpiece and environment).
    • Feedback from sensors and encoders returns to the Robot Controller to adjust motion in real time.
    • Programmer/Operator inputs commands and sequences into the Robot Controller; the controller outputs status and signals to PLCs for process coordination.

Question 4

  • 4.1 Write down FIVE duties that the cell operator must perform whilst working to ensure the quality of the product.
    • Verify correct raw materials and incoming stock against specifications.
    • Ensure proper machine setup, tooling, and offsets before starting, including zeroing and calibration.
    • Monitor process parameters (speeds, feeds, depths, temperatures, coolant levels) during production.
    • Inspect parts during production (in-process checks) to detect deviations early.
    • Maintain cleanliness and organization; report any tool wear, machine faults, or abnormal conditions immediately.
  • 4.2 Explain the consequences of the poor product quality due to material non-conformance. (3 × 1)
    • Increased scrap and rework, leading to higher manufacturing costs.
    • Production downtime and reduced throughput due to corrective actions.
    • Potential customer dissatisfaction, warranty costs, and possible loss of business or reputational damage.
  • 4.3 Explain what is meant by the following acronyms.
    • 4.3.1 JIT
    • Just-In-Time: a manufacturing philosophy aimed at producing only what is needed, when it is needed, and in the required quantities to minimize inventory and waste.
    • 4.3.2 TQM
    • Total Quality Management: an organization-wide approach focusing on long-term success through customer satisfaction, continuous improvement, involvement of all employees, and defect prevention.

Question 5

  • 5.1 Explain how CAD/CAM fits into a computer integrated manufacturing factory?
    • CAD (Computer-Aided Design) creates digital product geometry, tolerances, and documentation.
    • CAM (Computer-Aided Manufacturing) uses CAD data to generate machining instructions (tool paths, NC programs) and simulate manufacturing processes.
    • In a CIM factory, CAD/CAM provides a digital thread from design to manufacture, enabling automated scheduling, planning, and execution with minimal manual handoffs; it integrates with tooling, machines, and ERP/PLM systems to coordinate production.
  • 5.2 Draw a block diagram of CAD/CAM system technology showing data flow.
    • Textual block diagram:
    • Design Data (CAD) → Toolpath/NC generation (CAM) → NC Code/Post-Processing → CNC Machines (Milling/Turning) → Real-time Feedback/Monitoring → Quality/Measurements (CMM, sensors) → Data Store (PDM/PLM) → Enterprise Systems (ERP/MES).
    • Feedback loops exist from the shop floor back to CAM and CAD for design changes, process optimization, and documentation updates.
  • 5.3 Name the basic structure of the THREE geometric moulding types you could encounter in CAD/CAM application software.
    • Extruded (Prismatic) shapes: created by extending a 2D profile along a straight path, resulting in constant cross-section along the extrusion direction.
    • Revolved (Rotational) shapes: created by rotating a 2D profile around an axis to form solids of revolution.
    • Swept/Lofted (Free-form) shapes: created by sweeping a profile along a path or lofting between multiple profiles to create complex surfaces and solids.

Information Sheets

  • G-Codes (code, function)
    • G00: Rapid positioning
    • G01: Linear interpolation, controlled feed rate
    • G02: Circular interpolation CCW
    • G03: Circular interpolation CW
    • G04: Dwell for program duration
    • G17: XY plane select (milling)
    • G18: XZ plane select (milling)
    • G19: YZ plane select (milling)
    • G20: Inch units (sometimes denoted as unit selection in some documents)
    • G21: Metric units
    • G28: Return to reference point
    • G29: Return from reference point
    • G32: Thread cutting (lathe)
    • G40: Cutter compensation cancel
    • G41: Cutter compensation left
    • G42: Cutter compensation right
    • G90: Absolute programming
    • G91: Incremental programming
    • G94: Feed rate per minute
    • G70/G71: Unit control (document-specific: e.g., inch vs. metric in some manuals)
  • M-Codes (code, function)
    • M00: Program stop
    • M01: Optional stop
    • M02: End of program
    • M03: Spindle on CW
    • M04: Spindle on CCW
    • M05: Spindle off
    • M06: Tool change
    • M07: Mist coolant off
    • M08: Flood coolant on
    • M09: Coolant off
    • M19: Orient spindle
    • M30: End of program, reset program
  • Information sheets also include a mapping of IR pseudo-code terms (for industrial robot programming):
    • Program start followed by the program name
    • Non-action: semicolon followed by a comment
    • The numbering of the programming points
    • HOME: The HOME position of the industrial robot manipulator
    • CONT: Undefined motion (air movement)
    • LIN: Linear motion (straight line movement)
    • CIRC: Circular motion (arc movement)
    • PTP: Point-to-point (rapid or point-to-point move)
    • CONT: Undefined motion (air movement)
    • WAITFOR T: Wait for a time delay to elapse
    • WAITFOR_I: Wait for input from PLC
    • SEND O: Send output to PLC
    • GRIPPER O: Open the gripper
    • GRIPPER C: Close the gripper
    • SUCTION ON: Suction ON
    • SUCTION OFF: Suction OFF
  • Pseudo-code summary (IR program layout)
    • Program header and name
    • Comments indicated by non-action lines
    • Numbered programming points (POINTERS)
    • HOME position for safe startup
    • Motion commands: PTP, LIN, CIRC or undefined motion (CONT)
    • Transitions and I/O interactions: WAITFOR, SEND, GRIPPER, SUCTION
    • End conditions: reset or end program (M30 style)

How to use these notes for exam preparation

  • Understand the three CNC subsystems and their roles in a CNC machine tool and how they interact in a CIM environment.
  • Be comfortable with CIM system-level thinking: how multiple CNC machines, conveyors, and robots can be coordinated by a central controller.
  • Master the common G-code and M-code functions listed in the information sheets, and know how to interpret the purpose of each code in typical milling and turning programs.
  • Be able to explain basic CNC programming concepts (absolute vs incremental coordinates, Cartesian axes, and feed rates) and outline a typical NC programming workflow from design to production.
  • Know the standard robot programming concepts (TCP, end effector, common motion commands) and be able to describe simple sequences involving conveyors and obstacles.
  • Have a general sense of CAD/CAM integration in a CIM environment and the data flow from design to manufacture to quality assurance.
  • Practice translating Figure-based problems into step-by-step sequences and simple block diagrams to demonstrate your understanding of systems and data flow.